Lower Extremity Isometrics Prep for Running
By Kurt Jepson,
Ahhh April,…..
Exhale, chill for a bit, analyze past training plans and look to what you can do to make the upcoming season more successful than the one you just wrapped up. That includes preventing nagging injuries such as tendonitis and muscle strains resultant of dry land training routines.
Undoubtedly your upcoming plans include running, bounding and hiking. All can be considered “impact” activities for your lower extremities. The directional forces, kinematic components and subsequent loads of these crossover activities differ from those experienced while skiing. Despite your probable fitness peak at the conclusion of your comp season, you remain at risk for muscle-tendon injury if initial dry land conditioning is approached in a haphazard fashion.
Return to running programs are prevalent and logical. This site has excellent related posts for guidance regarding technique, frequency and duration. Focused exercise programs designed to improve the “durability” of lower extremity musculotendinous structures, are a bit tougher to track down. Improving the mechanical characteristics of structures which dissipate impact loading is an important component of early season training programs.
To begin, let’s look at the likely status of your extremities at the end of a long, physiologically stressful season.
Repetitive high intensity muscle contractions involve “Mechanocoupling” inputs to related tissues (Kahn, Scott, 2009). Loads are typically composed of tension (ground reaction forces), shear (contraction force) and compression loads (soft tissue/bone contact). Mechanocoupling forces which do not exceed the macrostructural tolerance of the involved tissue are beneficial. Cells are stimulated locally to release “signaling proteins”. Protein synthesis and cell adaptations result. The extent of the response is mediated by Mechanical Growth Factor (MGF), Insulin-like Growth Factor (Goldspink, 2003) and other substrates. If the Mechanocoupling loads exceed the structural tolerance of the tissue, cell disruption, dysfunction, and subsequent MGF mediated “scar” production ensues. Muscle-tendon “scar” lacks the elastic, tensile and energy storage characteristics required for sound function. The result is chronic or recurrent injury. A review of a prior post on this site entitled, “It`s just a strain,….” (June / 2021) discusses the related pathophysiology of contractile tissue injury.
If you experienced prolonged or excessive soreness, localized injury, or noticeable weakness during the season, you likely exceeded the load tolerance of that muscle-tendon unit acutely, or via “overuse”. Involved tissues have likely not returned to their normal biometric status due to in season demands. They will require specific stimulation to do so. Simply resting for a few weeks and then initiating a graduated return to training is not location or regeneratively specific.
Skiing by necessity requires repetitive concentric and eccentric muscle loading across joint structures via tendonous attachments. Forces can be quite pronounced and are based on velocity, terrain, snow conditions and tactics. Kinematic loads while skiing tend to be concentrated in the transverse and rotational planes. Classic technique involves more vertical plane loading than does skating.
Eccentric contractions while skiing produce significant “tension” and “shear” loads. Concentric contractions, especially when explosive, add pronounced tendon/bone interface “compression”, particularly if the tendon is changing direction over a bony prominence on the way to its insertion point (ie Patellar, Achilles, and Gluteal tendons). Modern technique involves all of these components and expose the athlete to tissue quality compromise if the loads produced are interpreted by the body as “injurious” verses “stimulating”. At the conclusion of a long competitive season, there has likely been compromise of musculotendinous tissue normalcy locally or regionally.
Bipedal activities such as running and bounding likewise require significant load dispersion. Kinematically, this is accomplished via pronounced eccentric muscle activity resulting in tension, shear and compression forces. If we begin these high demand activities in a state of compromised “durability”, we elevate the risk of running induced irritations.
There are obvious regions in the lower extremity vital to load dispersion while running.
The medial ankle/foot complex, the Achilles, the anterior knee/patellar region, and the lateral hip are tasked with dispersing ground reaction forces, decelerating mass, storing elastic energy, joint stabilization, balance assistance…. the list is endless! Exposure to potentially injurious Mechanocoupling load is substantial during dry land training. Contractile force up to five times body weight is required of the gluteal muscles to maintain a level pelvis while running (Byrne et al, Open Sport Med J 2010, Bergmann et al, J Biomech 1993). Hundreds of pounds of patellar load are produced during jumping, squatting and stair climbing (Cohen et al, AJSM 2001, Powers et al, JOSPT 2014). These are just two examples.
So how do we best prepare the lower extremities for a season of running, hiking and bounding?
Isometric loads have long been associated with desirable histologic changes in musculotendinous tissue (Cook et al Br J Sports Med 2014, Rio et al Br J Sports Med 2015, Reeves et al Mus Nerve 2003). By definition, isometric muscle contractions involve no joint movement or change in muscle length. Isometrics load is much easier to regulate in terms of force, duration and effort than concentric or eccentric resistance exercise. All exercise modes result in neural adaptions and histologic change, but isometrics allow the user enhanced control, producing desirable physiologic change without adverse cellular disruption. Isometric exercise should therefore be incorporated into pre-season programs to induce “durability” within musculotendinous tissue.
The intensity of contractile effort required for adequate remodeling stimulation of muscle and tendon tissue should range from 40-75% maximum volitional contraction (MVC) based on where the athlete is in her/his progression (Anderson, Visser, Fry). Efforts which exceed 75% MVC lend to undesirable physiologic effects and should not be utilized. Repetitions should be of a sustained nature to achieve desired cellular adaptions. Enhanced tendon stiffness, improvements in extracellular matrix, vascularity and viscoelastic properties have all been noted following bouts of 20-90 second isometric efforts by numerous investigators (Kubo 2001, Kjaer 2003, Boyer 2005). One set of 4 reps is typical. Sustained isometrics can be utilized numerous times a week as tendon tissue in particular has a low metabolic rate and requires limited recovery time following non injurious workloads, as prescribed above (Langberg et al 1999, Lavagnivo et al 2003). Because of the limits in tensioning (< peak MVC), shear (limited contractile movement), and compression (controlled via joint position utilized and < peak MVC), the risk of adverse Mechanocoupling is minimal compared with eccentric or concentric exercise modes.
Examples of target groups, joint positions and isometric resistance source are provided below. Do not exceed 75% MVC, resistance should be perceived as mild to moderate.
Quadriceps:
-Bilateral wall sit at ~70 degree knee angle to maximize patellar contact with femur while avoiding full passive pre-load of quadriceps tendon with deeper postures. Hold 90-60 sec x 4. If there is a history of patellofemoral issues, substitute with seated leg raises using a knee angle of 10-30 degrees. A small ankle weight may be used reducing hold time ~50% each rep.
-Goal is to reduce likelihood of Patellar Tendonitis (“Jumpers Knee”) via running bounding and improve patellar tracking.
Gluteus Medius and lateral Core:
-Side bridge holds with hip position 45 degree flexed and knees at 90 degrees to isolate anterior fibers of Gluteal groups (the most commonly injured). This position also limits Tensor muscle/Iliotibial Band contribution to the effort. Hold 30-60 sec x4 each side. Alternate exercise of side lying leg raise, knee 30 degrees, small ankle weight optional (< 5lbs), 45-90 sec x 4 each side.
-Goal of reducing likelihood of Gluteus Medius tendonitis, Trochanteric Bursitis and ITB Syndrome. Side bridging also produces high activation of various core groups with minimal lumbar discal loading.
Calf Raise:
-Use a stable elevation point to hold ankles (bilaterally) in neutral position (90 degree ankle appearance) to minimize tendon bone compression at calcaneus and proximal muscle shearing. Hold 90-60 sec x 4.
-Goal of preventing Achilles issues.
Ankle/Foot Inversion:
-Apply band resistance at forefoot with foot/ankle inverted ~ 10 degrees, position lower limb perpendicular to the band`s anchor point with enough tension to yield light to moderate resistance. Hold 60-90 sec x 4 each side.
-Goal of decreasing the likelihood of Posterior Tibial Tendonitis (“posteromedial shin splints”) and stabilizing the subtalar/mid foot articulations during stance and toe off.
Hamstrings/Hip Extensors:
-Supine bilateral bridge with feet on elevated surface and knees flexed ~60 deg. Hold 30-60 sec x 4. Alternate exercise of band holds or gym machine, knee at mid- range, 60-90 sec x 4 each side.
-Goal of reducing likelihood of hamstring strains and tendon injuries.
As previously mentioned, these activities can be utilized 2-3x/week. They should be performed for a month prior to implementing more dynamic activities such a box jumps, vigorous running, early bounding work outs, etc. After 4 weeks, a progression to eccentric activities is suggested and has been discussed on this site previously (May 2020). Low load, sustained isometrics have value throughout the year as they signal histologic adaptions within tendon tissue, enhancing form and function. I would suggest occasionally adding them to a standard gym program, focusing on any historically problematic areas.
Enjoy your down time!